QFileDialog memory leak?

Question

I'm just writing a small app in which I have function which looks like:

QString askForDir()
{
    return QFileDialog::getExistingDirectory(this, "Choose directory", QString(""));
}

Since I've added this function I've mentioned that memory allocation became pretty strange after using this function ( askForDir() ).
I use OS X Instruments app for debugging needs so here's what I've got:
Snapshot Peaks are the moments when askForDir() function works, I mean building dir-tree.
Between these peaks there are spaces where nothing happened, I mean app doing nothing, just waiting for other action from user.
As you can see memory allocation is growing. If you want numbers:

at 30sec - 91 Mb
at 50sec - 113 Mb
at 1m15sec - 135 Mb

Each time it grows at 22 Mb

I've tried to explore it and changed askForDir() function to smth like this:

QString askForDir()
{
    return "/Users/username/Desktop";
}

All I was speaking above disappeared. So, I concluded that the problem is in QFileDialog.

Here's what I'm using:

OS X 10.9.4
Xcode 5.1.1, Carbon
Qt 4.8.6

Has anyone else the same "problem"?

Qt 4.8.what? Using Carbon or Cocoa? With such issues you have to be very specific. — Kuba hasn't forgotten Monica, Jul 01 '14 at 14:52
I suggest recompiling qt for cocoa and trying again. If that still demonstrates this behavior, then it's a bug and you'll have to file a bug report. — Kuba hasn't forgotten Monica, Jul 01 '14 at 16:21
@KubaOber, sorry, but how can I do this? I installed qt4 from MacPorts — tema, Jul 01 '14 at 21:48

score 5 · Accepted Answer · answered Jul 04 '14 at 22:11

It seems, that I figure it out.
This is not a leak, neither a bug. If you open the notepad on windows xp, the memory usage is 4mb. Click on file->open and then the memory usage grows up to 9mb. Close the dialog and you can see the memory usage is not decreasing (or just a little around 8.9Mb). Windows is obviously caching/creating stuff on our back (caching for example). -> This is for the native usage.

For the non-native, It's the same. The first time you open a QFileDialog Qt library caches some icons for a later usage. This is at application level. This make navigation in the filedialog, as well as later on if you open the dialog again much faster. It's not a leak, when the app is closed everything is released.

Looks like the same thing happening everywhere, so, I think, the question is out of interest now.

QFileDialog memory leak?

1 Answers1